This invention relates to flexible radiant energy reflectors and to methods of manufacturing them.
Flexible radiant energy reflectors are useful for various purposes. They can be used for example in the production of curved mirrors for decorative purposes or for achieving special visual effects. A very important field of use is the production of curved concave reflectors for reflecting visual light beams from artificial light sources or for reflecting solar radiation, e.g. in solar heating installations.
It is known to use polished sheet metal as a flexible mirror. The use of a polished metal sheet is not satisfactory for some circumstances of use. One reason is the vulnerability of the reflective surface to mechanical damage. Another is the liability of the sheet to distortion consequent upon small changes in temperature.
For meeting high optical specifications it would be better to employ coated glass, the coating comprising a radiant energy reflecting layer which is exposed to radiant energy through the glass. However conventional glass mirrors are substantially non-flexible and in the known art of manufacturing curved glass reflectors, the practice is to cast molten glass into a mould of the desired curved form, or to subject the flat glass to bending forces while it is heated over an extended period of time and/or while the glass is at such elevated temperature that it assumes a desired permanent curvature. The curvature may e.g. be determined by a suitably shaped former. The light-reflecting coating must be applied to the curved glass after it has been bent, for otherwise the optical coating is liable to be spoiled.
These known methods of making curved glass reflectors are very expensive to perform under mass production conditions and to satisfy high product standards.
There is a need for a flexible reflector which incorporates a sheet of glass, and which benefits from the advantages that glass can confer, and which is nevertheless sufficiently flexible to permit it to be easily converted by a flexing operation, without need for the glass to be heated to a high temperature or even at all, into a reflector having the required curvature.